It's a lot, but if you're eating normally, it's not too much. Just make sure you're in touch with your surgeon's office, that you're taking a full complement of nutritional supplements and you're not deliberately starving yourself in hopes of losing weight fast.
I followed orders and lost 35 pounds my first month. And that's a lot, too.
You should be in regular contact with your doc and nutritionist. Just write everything down that you eat, make sure you hit your protein goals and your digestive process is working.
If you're vomiting and/or have diarrhea, that's cause for concern. But the first week or two can be weird. Your surgeon should have scheduled follow-up and you should be in touch regularly.
Better to be safe than sorry.